Five masked men smashed through a supermarket window before assaulting night staff, police have revealed.

Officers have now released further information over a violent robbery in Ongar, in the hope that more witnesses may come forward.

In a statement issued minutes ago police described how the gang, wearing balaclavas and black clothing, broke into and raided the Bansons Lane Sainsbury’s in the early hours of this morning.

One of the gang was holding what is believed to be a shotgun.

Three members of staff working in the store, which was closed, were tied up and one woman was assaulted.

The trio, the woman and her two male colleagues, were locked up in a store room whilst the gang stole a large quality of alcohol, cigarettes, microwaves, DVDs and other small items.

Investigating officer, DS Patrick Mullan, said that police would like to speak with anyone who used the cash machine from 9pm on Sunday.

He said: "This was a particularly nasty robbery in which the five men used excessive force against members of staff.

"We know that the gang broke into the supermarket at 12.40am and left at about 2am. The staff managed to raise the alarm at about 2.20am.

"We have no information about the type of vehicle the thieves used but we believe it was parked out of sight in the loading bay area. We have no descriptions other than that the men were all wearing balaclavas and black clothing.

"We want to hear from anyone who saw any suspicious activity near the supermarket, especially anyone who used the car park outside the store or from anyone who used the cash machine near the loading bay any time from 9pm on Sunday until 2am on Monday morning.”

Anyone with information should contact detectives at Loughton on 101 or call Crimestoppers anonymously on 0800 555111.